Portrait content

• Create a local store to remember videos that have been seen (#2518 (closed))
• Send GET request to return a list of all portrait videos (engine#1690 (closed))
• Filter out videos that have been seen locally (#2518 (closed))
• Implement a portrait bar component that shows available content
• Implement a portrait content swiper
• Implement custom transition for the swiper
• Implement paginator
• Fix gesture conflict with the menu and the portrait bar
• Refactor to add tap for next/prev post and swipe for next/prev user
• Fix paginator position on Android and add shadow
• Fix data not cleared on reload
• Mark as seen only the first element of focused swiper

closes #2391 (closed) #2554 (closed)